Use build rather than pep517 for building (#2784)

pep517 has been renamed to pyproject-hooks, and as a consequence all of
the deprecated functionality has been removed. build now provides the
functionality required, and since we are only interested in the
metadata, we can leverage a helper function for that. I've also removed
all of the subprocess machinery for calling the wrapping function, since
it appears to not be as noisy as pep517.

Author: s-t-e-v-e-n-k

pythonforandroid/pythonpackage.py

@@ -40,16 +40,14 @@
 import sys
 import tarfile
 import tempfile
-import textwrap
 import time
 import zipfile
 from io import open  # needed for python 2
 from urllib.parse import unquote as urlunquote
 from urllib.parse import urlparse
 
 import toml
-from pep517.envbuild import BuildEnvironment
-from pep517.wrappers import Pep517HookCaller
+import build.util
 
 
 def transform_dep_for_pip(dependency):
@@ -113,40 +111,7 @@ def extract_metainfo_files_from_package(
             )
             package = os.path.join(temp_folder, "package")
 
-        # Because PEP517 can be noisy and contextlib.redirect_* fails to
-        # contain it, we will run the actual analysis in a separate process:
-        try:
-            subprocess.check_output([
-                sys.executable,
-                "-c",
-                "import importlib\n"
-                "import json\n"
-                "import os\n"
-                "import sys\n"
-                "sys.path = [os.path.dirname(sys.argv[3])] + sys.path\n"
-                "m = importlib.import_module(\n"
-                "    os.path.basename(sys.argv[3]).partition('.')[0]\n"
-                ")\n"
-                "m._extract_metainfo_files_from_package_unsafe("
-                "    sys.argv[1],"
-                "    sys.argv[2],"
-                ")",
-                package, output_folder, os.path.abspath(__file__)],
-                stderr=subprocess.STDOUT,  # make sure stderr is muted.
-                cwd=os.path.join(os.path.dirname(__file__), "..")
-            )
-        except subprocess.CalledProcessError as e:
-            output = e.output.decode("utf-8", "replace")
-            if debug:
-                print("Got error obtaining meta info.")
-                print("Detail output:")
-                print(output)
-                print("End of Detail output.")
-            raise ValueError(
-                "failed to obtain meta info - "
-                "is '{}' a valid package? "
-                "Detailed output:\n{}".format(package, output)
-                )
+        _extract_metainfo_files_from_package_unsafe(package, output_folder)
     finally:
         shutil.rmtree(temp_folder)
 
@@ -461,51 +426,17 @@ def _extract_metainfo_files_from_package_unsafe(
         clean_up_path = True
 
     try:
-        build_requires = []
         metadata_path = None
 
         if path_type != "wheel":
-            # We need to process this first to get the metadata.
-
-            # Ensure pyproject.toml is available (pep517 expects it)
-            if not os.path.exists(os.path.join(path, "pyproject.toml")):
-                with open(os.path.join(path, "pyproject.toml"), "w") as f:
-                    f.write(textwrap.dedent(u"""\
-                    [build-system]
-                    requires = ["setuptools", "wheel"]
-                    build-backend = "setuptools.build_meta"
-                    """))
-
-            # Copy the pyproject.toml:
-            shutil.copyfile(
-                os.path.join(path, 'pyproject.toml'),
-                os.path.join(output_path, 'pyproject.toml')
-            )
-
-            # Get build backend and requirements from pyproject.toml:
-            with open(os.path.join(path, 'pyproject.toml')) as f:
-                build_sys = toml.load(f)['build-system']
-                backend = build_sys["build-backend"]
-                build_requires.extend(build_sys["requires"])
-
-            # Get a virtualenv with build requirements and get all metadata:
-            env = BuildEnvironment()
-            metadata = None
-            with env:
-                hooks = Pep517HookCaller(path, backend)
-                env.pip_install(
-                    [transform_dep_for_pip(req) for req in build_requires]
-                )
-                reqs = hooks.get_requires_for_build_wheel({})
-                env.pip_install([transform_dep_for_pip(req) for req in reqs])
-                try:
-                    metadata = hooks.prepare_metadata_for_build_wheel(path)
-                except Exception:  # sadly, pep517 has no good error here
-                    pass
-            if metadata is not None:
-                metadata_path = os.path.join(
-                    path, metadata, "METADATA"
-                )
+            # Use a build helper function to fetch the metadata directly
+            metadata = build.util.project_wheel_metadata(path)
+            # And write it to a file
+            metadata_path = os.path.join(output_path, "built_metadata")
+            with open(metadata_path, 'w') as f:
+                for key in metadata.keys():
+                    for value in metadata.get_all(key):
+                        f.write("{}: {}\n".format(key, value))
         else:
             # This is a wheel, so metadata should be in *.dist-info folder:
             metadata_path = os.path.join(

setup.py

@@ -22,9 +22,9 @@
 install_reqs = [
     'appdirs', 'colorama>=0.3.3', 'jinja2',
     'sh>=1.10, <2.0; sys_platform!="nt"',
-    'pep517', 'toml', 'packaging',
+    'build', 'toml', 'packaging',
 ]
-# (pep517 and toml are used by pythonpackage.py)
+# (build and toml are used by pythonpackage.py)
 
 
 # By specifying every file manually, package_data will be able to

tests/test_pythonpackage.py

@@ -42,7 +42,7 @@ def test_get_package_dependencies():
         if "MarkupSafe" in dep
     ]
     # Check setuptools not being in non-recursive deps:
-    # (It will be in recursive ones due to p4a's pep517 dependency)
+    # (It will be in recursive ones due to p4a's build dependency)
     assert "setuptools" not in deps_nonrecursive
     # Check setuptools is present in non-recursive deps,
     # if we also add build requirements:

tests/test_pythonpackage_basic.py

@@ -236,7 +236,7 @@ def run__get_system_python_executable(self, pybin):
             pybin,
             "-c",
             "import importlib\n"
-            "import json\n"
+            "import build.util\n"
             "import os\n"
             "import sys\n"
             "sys.path = [os.path.dirname(sys.argv[1])] + sys.path\n"
@@ -273,8 +273,8 @@ def test_systemwide_python(self):
             # Some deps may not be installed, so we just avoid to raise
             # an exception here, as a missing dep should not make the test
             # fail.
-            if "pep517" in str(e.args):
-                # System python probably doesn't have pep517 available!
+            if "build" in str(e.args):
+                # System python probably doesn't have build available!
                 pass
             elif "toml" in str(e.args):
                 # System python probably doesn't have toml available!
@@ -304,11 +304,8 @@ def test_venv(self):
             ])
             subprocess.check_output([
                 os.path.join(test_dir, "venv", "bin", "pip"),
-                "install", "-U", "pep517"
-            ])
-            subprocess.check_output([
-                os.path.join(test_dir, "venv", "bin", "pip"),
-                "install", "-U", "toml"
+                "install", "-U", "build", "toml", "sh<2.0", "colorama",
+                "appdirs", "jinja2", "packaging"
             ])
             sys_python_path = self.run__get_system_python_executable(
                 os.path.join(test_dir, "venv", "bin", "python")